JP6473855B1 - Aged egg yolk, processed food using the same, and method for producing aged egg yolk - Google Patents

Abstract

The aged egg yolk of the present invention is an aged egg yolk by mold, the salt content is 1% by mass or more and 12% by mass or less, and is measured by a predetermined method including treatment with a trichloroacetic acid solution, The absorbance of the mature egg yolk is 1.5 times or more and 15.0 times or less. According to the present invention, an aged egg yolk having a delicious taste and richness derived from egg yolk and a method for producing the same are provided.

Description

  The present invention relates to an aged egg yolk having umami and richness and having a good taste, a processed food using the same, and a method for producing an aged egg yolk.

Egg yolk has a unique mellow flavor and richness, and is eaten raw like egg rice or used as a food material or ingredient.
On the other hand, processed egg yolk processed raw egg yolk is known in order to enhance the flavor and richness of egg yolk.
For example, Patent Document 1 describes a processed egg yolk-containing liquid having a viscosity of 10 to 150 Pa · s (product temperature 20 ° C.), which is manufactured by heating and freezing an egg yolk-containing liquid containing a predetermined amount of sodium.
Patent Document 2 describes an egg yolk-containing liquid obtained by heating an emulsion obtained by mixing egg yolk, edible fat and water, and water at a predetermined heating rate and holding it at the maximum heating temperature for less than 5 minutes.

JP 2012-105641 A Japanese Patent Laying-Open No. 2015-96035

  The processed egg yolk-containing liquid and the egg yolk-containing liquid described in Patent Documents 1 and 2 are intended to be used as materials and ingredients for specific foods, and when added to various foods or as they are In that case, the umami, richness, and deliciousness were not fully demonstrated.

  In view of the circumstances as described above, an object of the present invention is to provide an aged egg yolk having an umami taste and a rich taste, a processed food using the same, and a method for producing the aged egg yolk.

  As a result of intensive studies to achieve the above object, the present inventors have a mild flavor like raw egg yolk by aging egg yolk using mold, especially straw, and have a unique umami taste and richness. It has been found that a mature egg yolk having a good taste can be obtained even if it is eaten as it is, or it can be used as a food material or ingredient, and the present invention has been completed.

That is, the present invention
(1) Aged egg yolk with mold,
The salt content is 1% by mass or more and 12% by mass or less,
An aged egg yolk having an absorbance of 1.5 times or more and 15.0 times or less with respect to the salted egg yolk measured by the following method.
<Measurement method of absorbance of aged egg yolk and salted egg yolk>
(1) Each of the mature egg yolk and the salted egg yolk having the same salt concentration (mass%) as the mature egg yolk is accurately weighed in an amount of 0.5 g, and each of the mature egg yolk and the salted egg yolk thus weighed is 20 mL of ion-exchanged water. Add and stir uniformly to suspend.
(2) 10 mL of a 10% by mass trichloroacetic acid solution is added to each of the matured egg yolk and the salted egg yolk, stirred again and uniformly suspended, and then allowed to stand for 30 minutes.
(3) The aged egg yolk and the salted egg yolk after standing are centrifuged at 3500 rpm for 10 minutes, and the aged egg yolk and the salted egg yolk after centrifugation are further filtered through a 0.45 μm filter to obtain a supernatant. .
(4) Using a spectrophotometer, the absorbance of each of the mature egg yolk and the salted egg yolk supernatant at 280 nm is measured, and the measured values are set as the absorbance of the mature egg yolk and the absorbance of the salted egg yolk, respectively. The absorbance of the mature egg yolk relative to the salted egg yolk is calculated by dividing the absorbance by the absorbance of the salted egg yolk.
(2) The mature egg yolk according to (1),
Aged egg yolk including salmon.
(3) The mature egg yolk according to (1) or (2),
An aged egg yolk in which the cocoon is an egg candy obtained by culturing koji mold with eggs.
(4) The mature egg yolk according to any one of (1) to (3),
Aged egg yolk having a content of glutamic acid, aspartic acid, valine, leucine, lysine and salts thereof as free amino acids contained in the aged egg yolk is 2 to 7 g per 100 g of protein.
(5) The mature egg yolk according to any one of (1) to (4),
Aged egg yolk having a pH of 4.5 or more and 7.0 or less.
(6) The mature egg yolk according to any one of (1) to (5),
Aged egg yolk having a viscosity measured at a product temperature of 20 ° C. of 1 Pa · S or more and 500 Pa · S or less.
(7) The mature egg yolk according to any one of (1) to (6),
An aged egg yolk containing at least one aroma component selected from tiglinaldehyde, 2-pentylfuran, methylpyrazine, trans-2- (2-pentenyl) furan, 2,4-heptadienal, methional, and phenylacetaldehyde.
(8) The mature egg yolk according to any one of (1) to (7),
Aged egg yolk having a protein content of 16% by mass or less.
(9) Processed food using the matured egg yolk according to any one of (1) to (8).
(10) producing a mixture of mold, egg yolk, and salt;
Producing a matured egg yolk having a salt content of 1% by mass to 12% by mass by aging the mixture while heating at 40 ° C to 65 ° C.
(11) A step of producing a mixture obtained by mixing a koji mold cultured with koji mold, egg yolk, and salt;
Producing a matured egg yolk having a salt content of 1% by mass to 12% by mass by aging the mixture while heating at 40 ° C to 65 ° C.
(12) The method for producing an aged egg yolk according to (11),
A method for producing an aged egg yolk, wherein the koji is an egg koji cultivated with eggs of koji mold,
It is.

  ADVANTAGE OF THE INVENTION By this invention, it becomes possible to provide the manufacturing method of matured egg yolk which has umami | taste and richness, and has good taste, processed food using the same, and matured egg yolk.

  Hereinafter, the present invention will be described in detail.

<Aged egg yolk>
The aged egg yolk of the present invention refers to an egg yolk ripened with mold using a cocoon or the like. By ripening the egg yolk, a decomposition product of the egg yolk component can be obtained abundantly as described later. For this reason, the matured egg yolk of the present invention contains a free amino acid as a decomposition product of egg yolk components, and has umami and richness derived from these in addition to the egg yolk-specific flavor. Thereby, it has the favorable taste that the flavor and richness derived from the flavor of egg yolk, a decomposition product, and richness were mixed.
The mature egg yolk of the present invention has smoothness such as raw egg yolk or semi-live egg yolk, and has a yellow to tan color.
The mature egg yolk of the present invention can be eaten as it is without cooking. Moreover, it can be added to cooked rice, noodles, salads, etc. like raw egg yolk, or used as a raw material or ingredient for other foods such as egg dishes and sweets.
Moreover, the matured egg yolk of the present invention is one that has been thawed after freezing, heated to inactivate mold-derived enzymes (for example, 75 ° C. or higher), and fungi are sterilized as long as the effects of the present invention are not impaired. It shall include those that have been heated to kill dead bacteria.

<Aged egg yolk with mold>
The mold-ripened egg yolk of the present invention refers to an egg yolk ripened by an enzyme generated by the mold, regardless of whether the mold is viable or dead, but from the viewpoint of strengthening the unique taste and richness, the mold is a live cell Is preferred.
The mold of the present invention is an edible mold usually used for fermentation and ripening of food, and all or part of the ripened egg yolk may be killed. Specifically, the ripening egg yolk by molds, mainly koji and the koji mold is cultivated classified as Aspergillus (Aspergillus) genus, cheese like blue mold and mildew belonging to Penicillium (Penicillium) genus breed Aged in addition to egg yolk.

<Yellow>
The egg yolk of the present invention may be any egg yolk that is generally in circulation, such as a raw egg yolk or a raw egg yolk that has been subjected to a predetermined treatment. Examples of the predetermined treatment include addition of salt and sugar, sterilization treatment such as pasteurization, freezing and thawing, drying and rehydration, desugaring treatment, and the like. These processes may be performed alone or in combination of two or more.
The egg yolk of the present invention contains egg yolk proteins such as phosvitin, vitellogenin, and ribetin, and lipids such as triacylglycerol and phospholipid. The lipid contained in egg yolk is hereinafter referred to as egg yolk lipid.

<Yellow protein breakdown product>
The mature egg yolk of the present invention is rich in egg yolk protein degradation products.
The egg yolk protein degradation product of the present invention refers to a component obtained by degrading egg yolk protein by the action of a proteolytic enzyme contained in mold. Examples of egg yolk protein degradation products include free amino acids and peptides such as dipeptides and tripeptides. Some free amino acids and peptides are known to have umami and richness. The aged egg yolk of the present invention has a deep taste by mixing these egg yolk protein degradation products.

<Free amino acids contained in aged egg yolk>
The free amino acid of the present invention refers to an amino acid that does not constitute a protein or peptide and exists in a free state and can be ingested as a food. The free amino acid of the present invention includes an amino acid obtained by decomposing egg yolk protein by the action of an enzyme.
Examples of the free amino acids include aspartic acid (Asp), threonine (Thr), asparagine (Asn), serine (Ser), glutamic acid (Glu), glutamine (Gln), proline (Pro), and glycine that constitute egg yolk protein. (Gly), alanine (Ala), valine (Val), cystine (Cys), methionine (Met), isoleucine (Ile), leucine (Leu), tyrosine (Tyr), phenylalanine (Phe), histidine (His), lysine (Lys), tryptophan (Trp), arginine (Arg) and the like.
The free amino acid of the present invention is not limited to the L form, and may be a D form or DL form which is an optical isomer.
The free amino acid of the present invention may be a food-acceptable free amino acid salt. Examples of free amino acid salts include salts with inorganic bases and salts with inorganic acids. Examples of the salt with an inorganic base include a salt with an alkali metal such as sodium, potassium and lithium, a salt with an alkaline earth metal such as calcium and magnesium, and an ammonium salt. Examples of the salt with an inorganic acid include salts with sulfuric acid, nitric acid, phosphoric acid and the like.

<Free amino acids / glutamic acid, aspartic acid, valine, leucine and lysine and their salts>
The free amino acids of the present invention include glutamic acid, aspartic acid, valine, leucine and lysine and salts thereof. For example, glutamic acid and aspartic acid have a unique taste. For example, valine, leucine, and lysine can be added in appropriate amounts, thereby providing richness along with bitterness and deepening the taste. A deep taste can be obtained by mixing the amino acids in a complex range within a predetermined content range.

<Contents of glutamic acid, aspartic acid, valine, leucine and lysine, and salts thereof>
Further, in the present invention, the content of glutamic acid, aspartic acid, valine, leucine, and lysine as free amino acids and salts thereof is 2 to 7 g per 100 g of protein, and further 2 to 6 g and 2 to 5 g. There should be. Thereby, glutamic acid, aspartic acid, valine, leucine, lysine and the like can be sufficiently contained, and the umami and richness can be enhanced, and the bitterness and puffyness caused by excessive free amino acids can be suppressed.
The content of glutamic acid and aspartic acid, which are amino acids related to umami, is preferably 0.8 g or more and 2.5 g or less per 100 g of protein.
The content of valine and leucine, which are amino acids related to bitterness and richness, is preferably 0.7 g or more and 2.5 g or less per 100 g of protein.
The free amino acid content may be determined by a commonly used measurement method, and can be measured, for example, using an amino acid automatic analyzer as in Examples 1 and 2 and Comparative Examples described later.
In addition, the total content of free amino acids per 100 g of the protein of the present invention is 2.5 g to 10 g, preferably 3 g to 9.5 g, and more preferably 4 g to 9.5 g.

<Absorbance of Aged Yolk to Salted Yolk>
In the present invention, the absorbance value of the matured egg yolk relative to the salted egg yolk, which is measured and calculated by the following method, is used as an index of the content of the whole egg yolk protein degradation product including free amino acids and peptides.
The absorbance of the present invention refers to the absorbance at 280 nm of a solution prepared by adding a TCA (trichloroacetic acid) solution to salted egg yolk and mature egg yolk, and specifically, the absorbance measured by the following measurement method. By adding a TCA solution to a sample such as salted egg yolk and mature egg yolk, proteins in the sample can be precipitated. For example, a supernatant containing non-protein nitrogen compounds such as amino acids, peptides, amines, ammonia, urea, etc. can get. By measuring the absorbance of the supernatant, the whole egg yolk protein degradation product containing free amino acids can be quantified.
The salted egg yolk of the present invention is used as a control for an ripened egg yolk, which is a liquid egg yolk with only the same content of salt as that of an ripened egg yolk, without added mold such as strawberries. Say.
The liquid egg yolk refers to those obtained by splitting the eggs of birds such as chickens and separating the egg white, and include those that have been split and stored after refrigeration for a predetermined period of time and those that have been thawed after freezing.

<Measurement method of absorbance of aged egg yolk with respect to salted egg yolk>
(1) 0.5 g of each of the mature egg yolk and the salted egg yolk having the same salt concentration (mass%) as the mature egg yolk is precisely weighed, and 20 mL of ion-exchanged water is added to the mature egg yolk and the salted egg yolk Add in portions and stir to suspend uniformly.
(2) Add 10 mL of the 10% by mass TCA solution to the matured egg yolk and the salted egg yolk, and stir again to make it uniformly suspend, and then let stand for 30 minutes.
(3) The aged egg yolk and the salted egg yolk after standing are centrifuged at 3500 rpm for 10 minutes, and the aged egg yolk and the salted egg yolk after centrifugation are further filtered through a 0.45 μm filter to obtain a supernatant. .
(4) Using a spectrophotometer, the absorbance of each of the mature egg yolk and the salted egg yolk supernatant at 280 nm is measured, and the measured values are set as the absorbance of the mature egg yolk and the absorbance of the salted egg yolk, respectively. The absorbance of the mature egg yolk relative to the salted egg yolk is calculated by dividing the absorbance by the absorbance of the salted egg yolk.
Thus, by determining the absorbance using salted egg yolk as a control, the egg yolk protein degradation product increased by aging can be quantitatively determined.
In addition, after separating the supernatant, the absorbance and ratio of a fraction having a molecular weight in a predetermined range (for example, a molecular weight of 3000 or less) can be obtained by performing a process such as ultrafiltration.

<Range of absorbance of mature egg yolk relative to salted egg yolk>
The above-mentioned absorbance of the mature egg yolk of the present invention is preferably 1.5 times or more and 15.0 times or less, more preferably 1.5 times or more and 10.0 times or less with respect to the absorbance of the salted egg yolk. It is good that they are 5 times or more and 5.0 times or less.
When the absorbance is 1.5 times or more, an aged egg yolk rich in egg yolk protein degradation products can be obtained. For example, peptides such as dipeptides and tripeptides are also known to have umami and richness. For this reason, in addition to the said amino acid, the richness and richness of a mature egg yolk can be improved further by containing abundant peptides.
When the absorbance is 15.0 times or less, it is possible to suppress bitterness and puffing due to excessive egg yolk protein degradation products.
The absorbance in the fraction having a molecular weight of 3000 or less in the supernatant of the mature egg yolk of the present invention is preferably 1.2 to 5.0 times that of the salted egg yolk. It is good that they are 4 times or more and 3.0 times or less. Thereby, it can be set as the mature egg yolk which abundantly contains a low molecular weight amino acid and peptide, and can further improve umami and richness.

<Salt content of aged egg yolk>
Furthermore, the matured egg yolk of the present invention contains a predetermined range of salt.
The salt content of the mature egg yolk of the present invention is 1 to 12% by mass, preferably 2 to 10% by mass, and more preferably 3 to 8% by mass.
Salt content is 12 mass% or less, saltiness can be suppressed, and the original flavor of egg yolk, the umami | flavor origin derived from an egg yolk protein degradation product, richness, etc. can be emphasized. In addition, the amount of salt intake when eaten as it is can be suppressed, and the total salt content can be easily adjusted when combined with other foods.
When the salt content is 1% by mass or more, an aged egg yolk excellent in storage stability is obtained, which is preferable from the viewpoint of distribution. Further, by adding sodium chloride so that the content becomes the above during ripening, enzymatic degradation of egg yolk protein is promoted, and a desired ripened egg yolk can be obtained in a relatively short ripening period.

<Measurement method of salt content of aged egg yolk>
The value of the salt content of the mature egg yolk of the present invention is a value measured using the Mole method.

<PH of aged egg yolk>
The pH of the mature egg yolk of the present invention is preferably 4.5 or more and 7.0 or less, and preferably 5.0 or more and 6.5 or less. By adjusting the pH of the mature egg yolk to 4.5 or more and 7.0 or less, the acidity is suppressed, and it becomes easy to feel the mellow flavor peculiar to egg yolk. Furthermore, by adjusting the pH to 5.0 or more and 6.5 or less, the pH of the mature egg yolk can be brought closer to the pH of the normal egg yolk (about 6 to 7). It becomes easy to obtain.

<Measurement method of pH of ripening egg yolk>
The pH value of the mature egg yolk of the present invention is a value measured using a pH meter (desktop pH meter F-72 manufactured by Horiba, Ltd.) when the pressure is 1 atm and the product temperature is 20 ° C.

<Aging egg yolk viscosity>
The viscosity of the mature egg yolk of the present invention is a viscosity measured at a product temperature of 20 ° C., which is preferably 1 Pa · S or more and 500 Pa · S or less, and preferably 1.5 Pa · S or more and 400 Pa · S or less. It is preferably 5 Pa · S or more and 100 Pa · S or less, and more preferably 1.5 Pa · S or more and 30 Pa · S or less. The viscosity of the present invention is measured with a BH viscometer. The rotor is, for example, No. 5 or the like can be appropriately selected, and the number of rotations can also be appropriately selected. This makes it possible to obtain an aged egg yolk that is easy to feel the viscosity and mellowness of raw egg yolk or semi-live egg yolk and is easy to eat as it is, and has a good touch.

<Aged yolk yolk lipid oxide>
In the mature egg yolk of the present invention, the amount of egg yolk lipid oxide produced by oxidizing the egg yolk lipid is small.
Here, the mechanism of egg yolk lipid oxidation will be described. For example, in the case of an unsaturated fatty acid, a lipid radical is generated by a hydrogen abstraction reaction of a saturated bond, an autoxidation reaction is started, and a peroxide (primary oxidation product) is generated. Further, a peroxide as a primary oxidation product is polymerized, or a secondary oxidation product such as a carbonyl compound is generated by breaking a carbon chain at a reaction site. Furthermore, among carbonyl compounds that are secondary oxidation products, aldehydes react with amino groups such as surrounding proteins (aminocarbonyl reaction), and tertiary oxidation products (aminocarbonyl reaction products) are generated. This tertiary oxidation product is one of the causative substances of property changes such as flavor deterioration and fading.
As described above, the mature egg yolk of the present invention has a high protease activity in order to sufficiently degrade the egg yolk protein. In addition to having an umami improving effect, a protease has an oxidation defense mechanism of degrading a molecule damaged by oxidative damage, and has a very excellent antioxidant activity. For this reason, in the matured egg yolk of the present invention, the oxidation of egg yolk lipid is suppressed, the production of tertiary oxidation products (egg yolk lipid oxide) exhibiting an astringent taste and the like is reduced, and a matured egg yolk with better taste is obtained.

<Evaluation of egg yolk lipid oxide / relative fluorescence intensity>
In order to evaluate the production amount of egg yolk lipid oxide in the mature egg yolk of the present invention, the value of relative fluorescence intensity can be measured. The relative fluorescence intensity is an index indicating the content of the tertiary oxidation product (aminocarbonyl reaction product). A method for measuring the relative fluorescence intensity will be described later.
The relative fluorescence intensity is preferably 1.5 × 10 ⁻² or more and 5.0 × 10 ⁻² or less, and more preferably 2.0 × 10 ⁻² or more and 4.0 or less × 10 ⁻² . Thereby, the oxidation of egg yolk lipid is suppressed, the astringent taste is suppressed, and an aged egg yolk having a strong taste and richness can be obtained.

<Aroma components contained in aged egg yolk>
The mature egg yolk of the present invention is at least one fragrance component selected from tiglinaldehyde, 2-pentylfuran, methylpyrazine, trans-2- (2-pentenyl) furan, 2,4-heptadienal, methional, and phenylacetaldehyde. It may contain.
The aroma component is mainly generated by heating the mature egg yolk during aging. By containing the above fragrance component, it is possible to impart a fragrant flavor in which egg yolk is appropriately heated.
The aroma component of the present invention can be measured, for example, by solid phase microextraction-gas chromatographic analysis mass spectrometry.

<Protein content of aged egg yolk>
In the matured egg yolk of the present invention, the egg yolk protein is sufficiently decomposed, so that the content of egg yolk protein may be smaller than that of normal egg yolk.
The protein content in the mature egg yolk of the present invention is preferably 16% by mass or less, and preferably 15.5% by mass or less. Thereby, an aged egg yolk rich in egg yolk protein breakdown product is obtained.

<Method for measuring protein content of aged egg yolk>
The protein content of the mature egg yolk of the present invention is a value measured by the Kjeldahl method.

<Processed food>
The processed food of the present invention is characterized by using the aged egg yolk. The form of the processed food is not particularly limited. For example, seasonings such as mayonnaise, tartar sauce, dressing, barbecue sauce, sauce for pasta such as carbonara sauce, sauce for egg over rice, egg binding, spread, etc. Processed egg products, sauce for egg rice, potato salad, macaroni salad and the like.
In particular, since the effects of the present invention can be easily achieved, it may be used for processed foods containing egg yolks such as mayonnaise and carbonara sauce.

<Other additives>
For example, thickening polysaccharides, sucrose, lactose, dextrin and the like can be added to the mature egg yolk of the present invention as long as the effects of the present invention are not impaired.

<Method for producing aged egg yolk>
The method for producing an aged egg yolk according to the present invention comprises a step of producing a mixture in which mold, egg yolk and salt are mixed, and the mixture is aged while being heated at 40 ° C. or more and 65 ° C. or less, so that the salt content is increased. And a step of producing an aged egg yolk having a mass of 1% by mass or more and 12% by mass or less. This will be specifically described below.

<Process for producing a mixture>
First, mold, egg yolk, and salt are uniformly mixed according to a conventional method to produce a mixture.
The ratio of each material in a mixture will not be specifically limited if the said matured egg yolk can be manufactured.
For example, the content of egg yolk is preferably 50% by mass to 95% by mass, and more preferably 80% by mass to 90% by mass.
The content of sodium chloride is appropriately adjusted so that the ripened egg yolk has the above-mentioned sodium chloride content. For example, it is preferably 1% by mass to 10% by mass, and more preferably 1% by mass to 6% by mass.
In addition to the above materials, a predetermined amount of water may be added to the mixture of the present invention.
The mixture of the present invention may be stirred using a general stirrer such as a kneader or a mixer. Thereby, each material is mixed uniformly and ripening can be advanced.

<Mold contained in the mixture>
Examples of the mold contained in the mixture of the present invention include koji mold, blue mold, and white mold that can produce an egg yolk proteolytic enzyme. As for the koji mold, it is mixed as a koji described later.
Examples of Aspergillus include Aspergillus oryzae and Aspergillus sojae , as well as Aspergillus luchuensis and Aspergillus luchuensis. Aspergillus luchuensis and its mutants .
Examples of blue mold and white mold include edible mold belonging to the genus Penicillium .

<Amber contained in the mixture>
The mixture of the present invention can be produced by mixing salmon, egg yolk, and salt.
The koji of the present invention refers to a koji obtained by inoculating the koji mold in a medium such as a protein material such as egg or bean or a carbohydrate material such as rice.
As the koji used in the present invention, for example, an egg koji obtained by culturing koji mold in eggs, a rice koji obtained by culturing koji mold in rice, a soybean koji obtained by culturing koji mold in soybean, or a wheat koji obtained by culturing koji mold in wheat Can do. Aspergillus oryzae selectively produces an enzyme according to the type of culture medium and culture conditions. For this reason, each cocoon contains different enzyme groups, and by using different cocoons, aged egg yolks with different flavors and tastes can be obtained.
In the present invention, an egg yolk or rice bran is preferably used because an aged egg yolk having umami and richness derived from egg yolk is easily obtained. Aspergillus contained in egg yolk can produce many proteolytic enzymes suitable for degrading egg yolk protein. That is, by using egg yolk, egg yolk protein is efficiently decomposed and ripening can proceed.
For example, when egg yolk is used, the content of the cocoon is preferably 1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less.

<Other materials contained in the mixture>
In the step of producing the mixture of the present invention, other materials can be appropriately selected and added in addition to the above-described materials as long as the effects of the present invention are not impaired.
In addition, another carbon source or nitrogen source or inorganic salts may be added to the above mixture to enhance the enzyme activity.
Moreover, you may add suitably additives, such as a pH adjuster and antiseptic | preservative.

<Process for producing aged egg yolk>
Following the step of producing the mixture, the mixture is aged while being heated at 40 ° C. or more and 65 ° C. or less, thereby producing an aged egg yolk having a salt content of 1% by mass to 12% by mass.

<Aging>
The ripening of the present invention means that egg yolk components such as egg yolk protein are decomposed by the action of an enzyme produced by mold, and egg yolk protein degradation products and the like are generated without rotting. Thereby, a wide variety of egg yolk protein degradation products according to the type of mold are generated, and an aged egg yolk having a complex taste can be obtained.
The aging in the present invention may be performed in a state in which mold such as Neisseria gonorrhoeae has been killed, but it is preferable that at least a part remains alive. Thereby, peculiar taste and richness can be strengthened.

<Aging temperature>
The aging temperature of the present invention is 40 ° C. or more and 65 ° C. or less, preferably 45 ° C. or more and 60 ° C. or less, and more preferably 50 ° C. or more and 60 ° C. or less.
Enzyme can be activated by setting it as 40 degreeC or more. Moreover, the matured egg yolk which has a fragrant flavor is obtained by the said aromatic component being produced | generated by heating. Furthermore, since a certain amount of bactericidal effects can be obtained against germs other than Neisseria gonorrhoeae, the risk of contamination during processing and manufacturing is reduced.
By setting the temperature to 65 ° C. or less, heat denaturation of egg yolk protein can be suppressed, and a smooth feeling close to that of raw egg yolk can be maintained. Moreover, the production | generation of an egg yolk lipid oxide can be suppressed and an astringent taste can be suppressed.
The aging temperature of the present invention is a temperature that is maintained substantially constant during the aging time described below, but may be increased and decreased within the above range.
Further, by aging the mixture while heating at the above aging temperature, the temperature becomes the optimum temperature of the enzyme and the degradation rate can be improved, so that the aging period can be shortened. Furthermore, since the aging period is shortened, the amount of sodium chloride added can be reduced from the viewpoint of storage stability, so that it is possible to prevent umami and richness from being damaged by excessive saltiness.

<Aging time>
The aging time of the present invention is preferably from 24 hours to 300 hours, preferably from 24 hours to 240 hours, and preferably from 48 hours to 192 hours.
By setting the aging time to 24 hours or more and 300 hours or less, the content of free amino acid and the absorbance value can be within the above-mentioned ranges. Furthermore, by setting the aging time to 240 hours or less and 192 hours or less, the production of egg yolk lipid oxide can be suppressed and the astringent taste can be suppressed.

<Operational effect of the present invention>
As described above, the matured egg yolk of the present invention is produced by aging while heating egg yolk to which mold such as strawberries is added at 40 ° C. or higher and 65 ° C. or lower. By aging in such a temperature range, the proteolytic enzyme and the like contained in the koji can be activated, and the egg yolk protein can be sufficiently degraded.
Thereby, as for the matured egg yolk of this invention, the light absorbency of the supernatant in the process by a TCA solution becomes 1.5 times or more and 15.0 times or less with respect to salted egg yolk. That is, the matured egg yolk of the present invention has umami and richness derived from egg yolk protein degradation products such as free amino acids and peptides. Furthermore, these can be mixed with the original flavor of egg yolk and a mature egg yolk having a deep taste can be obtained.
Furthermore, the matured egg yolk of the present invention contains 1% by mass or more and 12% by mass or less of salt. Thereby, while being able to ensure the preservability required for distribution | circulation, saltiness can be suppressed and the original taste of an ripened egg yolk can be emphasized. Accordingly, in addition to the umami and richness derived from the yolk protein degradation product, a matured yolk with good taste that is derived from the original umami and flavor of egg yolk can be obtained.
Thus, according to the present invention, a mature egg yolk that has a deep taste even if it is eaten as it is, and exhibits a unique flavor and richness even when used as a material or ingredient of other foods, and a mellowness peculiar to egg yolk. Can be obtained.

  Hereinafter, the present invention will be further described based on examples and the like. The present invention is not limited to these.

<Test Example 1: Evaluation of egg yolk protein degradation product>
As Test Example 1, in order to confirm whether or not an egg yolk protein degradation product is produced in the matured egg yolk, using Examples 1 and 2 and Comparative Example, in the measurement of protein content, composition analysis of free amino acids, and treatment with TCA solution The absorbance of the supernatant was measured.

[Example 1]
First, dried whole eggs (product name: frozen cooked egg powder, manufactured by Kewpie Co., Ltd., hereinafter referred to as CEP) melted with water to give a water content of 30%, Aspergillus luchuensis (manufactured by Matsunosuke Shotaguchi Co., Ltd.) was inoculated and cultured at 32 ° C. to 34 ° C. for about 42 hours to obtain egg yolk.
Subsequently, 86 parts by mass of liquid egg yolk is mixed with 4 parts by mass of salt and 10 parts by mass of egg yolk, aged for 3 days in a 55 ° C. incubator, frozen once in a freezer at −30 ° C. and then thawed. The aged egg yolk of Example 1 was obtained. In addition, what was preserve | saved the obtained mature egg yolk in a 4 degreeC low temperature room | chamber was used for each analysis mentioned later.
The salt content of the resulting mature egg yolk was 4% by mass.

[Example 2]
The mature egg yolk of Example 2 was produced in the same manner as in Example 1 except that the aspergillus aspergillus Aspergillus luchuensis of Example 1 was changed to a miso koji mold (manufactured by Matsunosuke Shojiguchi Co., Ltd.).
The salt content of the resulting mature egg yolk was 4% by mass.

[Comparative Example 1]
4 parts by mass of salt and 10 parts by mass of dried whole egg (CEP) were mixed with 86 parts by mass of liquid egg yolk to obtain salted egg yolk containing CEP (Comparative Example 1). That is, the salted egg yolk of Comparative Example 1 was maintained for 3 days in a thermostat at 55 ° C. in the same manner as in the Example, using CEP instead of the egg yolk in the Example.
The salt content of the obtained salted egg yolk containing CEP was 4% by mass.

[Measurement of protein content]
The protein contents of Examples 1 and 2 and Comparative Example 1 were calculated by quantifying nitrogen by the Kjeldahl method and multiplying by a protein conversion factor of 6.25.
The calculation results are shown in Table 1. As shown in the table, the protein (nitrogen quantitative conversion) content per 100 g of the samples of Examples 1 and 2 was 15.0 g. On the other hand, the protein content per 100 g of the sample of Comparative Example 1 was 17.1 g.

[Composition analysis of free amino acids]
Then, in order to confirm that egg yolk protein was decomposed | disassembled and the free amino acid was produced | generated, the amount of free amino acids per 100g of samples of Examples 1, 2 and Comparative Example 1 was measured with the amino acid automatic analyzer. Table 2 shows the results of calculating the amount of each free amino acid per 100 g of the proteins of the samples of Examples 1 and 2 and Comparative Example 1 using the value of the free amino acid of each sample and the value of the protein content measured above. As shown in the table, the total content of free amino acids in the samples of Examples 1 and 2 was 9640 mg and 5487 mg per 100 g of protein, respectively. On the other hand, the total content of free amino acids in Comparative Example 1 was 2181 mg per 100 g of protein, which was less than Examples 1 and 2.
Furthermore, the total contents of Glu, Asp, Val, Leu and Lys in the samples of Examples 1 and 2 were 4160 mg and 2307 mg per 100 g of protein, respectively. In contrast, in Comparative Example 1, the total content of Glu, Asp, Val, Leu, and Lys was 924 mg per 100 g of protein, which was also less than Examples 1 and 2.
Thereby, it was confirmed that Examples 1 and 2 contained abundant free amino acids including Glu, Asp, Val, Leu, and Lys as compared with Comparative Example 1.

[Treatment with TCA solution and measurement of absorbance]
Subsequently, in order to confirm egg yolk protein degradation products other than free amino acids, Examples 1, 2 and Comparative Example 1 and a sample of salted egg yolk as a control were treated with a TCA solution to precipitate proteins. Absorbance at a wavelength of 280 nm was measured. In addition, as salted egg yolk, a liquid egg yolk prepared by adding only salt to 4% by mass without adding sputum or CEP was prepared.
First, 0.5 g of each sample was precisely weighed, and 20 mL of ion-exchanged water was added. After stirring these with a vortex mixer, 10 mass% TCA was added 10 mL at a time, stirred again with a vortex mixer, and allowed to stand for 30 minutes. Thereafter, the mixture was centrifuged at 3500 rpm for 10 minutes, and further filtered through a 0.45 μm pore size filter to obtain a supernatant.
Subsequently, the absorbance of the supernatant was measured using a spectrophotometer (product name: UV-2450, manufactured by Shimadzu Corporation).

Furthermore, in order to confirm the approximate concentration of free amino acids contained in the supernatant of the TCA solution and components (free amino acids, dipeptides, tripeptides, etc.) having a molecular weight of 3,000 or less among the peptides, Was ultrafiltered, and the absorbance at a wavelength of 280 nm of a fraction having a molecular weight of 3000 or less was measured. For ultrafiltration, a centrifugal ultrafiltration filter (product name: Amicon Ultra UltraCel 3K, manufactured by Merck & Co., Inc.) was used.
Table 3 shows the measurement results of the absorbance at a wavelength of 280 nm of the fractions of Examples 1 and 2, Comparative Example 1, and salted egg yolk (control) having a molecular weight of 3000 or less.

  Further, Table 4 shows the results of dividing the absorbance values of Examples 1 and 2 and Comparative Example 1 by the absorbance value of salted egg yolk.

As shown in Table 3 and Table 4, the absorbances of the supernatants of Examples 1 and 2 were 0.473 and 0.305, respectively, and the absorbance of the supernatant in salted egg yolk was 0.120. Both 94 times and 2.54 times were confirmed to increase significantly. Similarly, it was confirmed that the absorbances of the fractions of Examples 1 and 2 having a molecular weight of 3000 or less were increased as compared with the salted egg yolk.
In contrast, the absorbance of the supernatant of Comparative Example 1 to which CEP was added instead of sputum was 0.145, 1.21 times the absorbance of the supernatant in salted egg yolk 0.120, It was confirmed to be a low value of less than 5 times. Similarly, the absorbance of the fraction having a molecular weight of 3000 or less in Comparative Example 1 was 1.16 times that of the salted egg yolk, and it was confirmed that there was almost no change.
Thereby, in Examples 1 and 2, it was confirmed that free amino acids and peptides having umami and richness were contained more abundantly than Comparative Example 1, and the degradation of the protein was promoted by aging.

  Furthermore, when the matured egg yolk of Examples 1 and 2 was eaten, the mellow flavor, richness and slight bitterness that seem to be derived from free amino acids and peptides were added to the mellow flavor peculiar to egg yolk. It had a completely different depth. Furthermore, since the matured egg yolk of Examples 1 and 2 exhibited a unique fragrant flavor, the aroma components were measured as follows.

[Measurement of aroma components]
The aroma components of Examples 1 and 2 and Comparative Example 1 were measured according to the following measuring method.
(Measurement method of aroma components)
The fragrance components of the fragrance components of Examples 1 and 2 and Comparative Example 1 were measured by solid phase microextraction-gas chromatograph mass spectrometry (SPME-GC-MS) according to the following conditions.
<Analysis conditions>
(1) Separation and concentration method of fragrance components Separation and concentration of fragrance components were performed by a solid-phase microextraction method using SPME fibers and a volatile component extraction apparatus according to the following conditions.
<Solid-phase microextraction conditions>
SPME fiber: SPME fiber (product name: StableFlex 50/30 μm) having a double-layer coating with a divinylbenzene-dispersed polydi-6methylsiloxane layer with a thickness of 50 μm on the outside and a Carboxen-dispersed polydimethylsiloxane layer with a thickness of 30 μm on the inside DVB / Carboxen / PDMS (Sigma-Aldrich))
・ Volatile component extraction device: Combi PAL, manufactured by CTC Analytics ・ Preheating: 40 ° C., 15 min
・ Agitation speed: 500 rpm
・ Volatile component extraction: 40 ℃, 20min
・ Desorption time: 10 min
(2) Method for measuring aroma components Each peak area is measured according to the following conditions using a gas chromatograph method and a mass spectrometry method.
The quantitative ion mass of each component is as follows.
・ Tigraldehyde quantitative ion mass m / z84
2-pentylfuran quantitative ion mass m / z 81
・ Methylpyrazine quantitative ion mass m / z94
Trans-2- (2-pentenyl) furan quantitative ion mass m / z 136
2,4-heptadienal quantitative ion mass m / z 55
Methional quantitative ion mass m / z 79
・ Phenylacetaldehyde quantitative ion mass m / z 91
<Gas chromatographic conditions>
Measuring instrument: Agilent 7890B (manufactured by Agilent Technologies)
Column: Capillary column with a liquid phase consisting of polyethylene glycol coated on the inner wall with a film thickness of 0.25 μm, length of 30 m, diameter of 0.25 mm, film thickness of 0.25 μm (product name: SOLGEL-WAX (manufactured by SGE)) 30m, aperture 0.25mm, film thickness 0.25μm)
・ Temperature condition: 35 ° C. (5 min) hold → 5 ° C./min temperature rise to 60 ° C. → 10 ° C./min temperature rise to 200 ° C. → 15 ° C./min temperature rise to 220 ° C. then hold 9.7 min at 220 ° C. ・ Carrier : He gas, gas flow rate: 1.2 mL / min
・ Injection method: Pulsed / Splitless: Splitless 1.6min hold → Purge hold at 50mL / min Pulse pressure 120kPa 1.6min hold → Hold at 60kPa (at start)
Inlet temperature: 250 ° C
Work station MSD ChemStation Build 75 (Agilent Technologies, Inc.)
<Mass analysis conditions>
Mass spectrometer: Quadrupole mass spectrometer (Product name: Agilent 5977A (manufactured by Agilent Technologies))
Scan mass m / z 29.0-290.0
・ Ionization method EI (ionization voltage 70eV)
As a result, in Examples 1 and 2, all of fragrance components were tiglinaldehyde, 2-pentylfuran, methylpyrazine, trans-2- (2-pentenyl) furan, 2,4-heptadienal, methional, and phenylacetaldehyde. was detected. On the other hand, in the comparative example 1, said aromatic component was not detected.
Thus, in Examples 1 and 2, it was confirmed that the aroma component that was not detected in Comparative Example 1 was generated, and thus the aromatic flavor peculiar to the matured egg yolk was exhibited.

<Test Example 2: Examination of absorbance of each sample with respect to salted egg yolk>
From the results of the absorbance measurement in Test Example 1 and the like, it was confirmed that many egg yolk protein degradation products were produced in the mature egg yolk of the present invention. Then, the light absorbency with respect to salted egg yolk was examined like the test example 1 with respect to the matured egg yolk manufactured on various conditions.

[Production of Examples 3 to 5 and measurement of absorbance]
In order to investigate the relationship between the aging temperature and the absorbance, Examples 3 to 5 having different aging temperatures were produced. In the present embodiment, the aging temperature is the temperature in the thermostatic chamber during aging.
First, an egg cake was obtained in the same manner as in Example 2 except that the medium was heat-sterilized with steam before inoculating the koji mold.
Next, a mixture containing 3% by mass of egg yolk, 83% by mass of egg yolk, 4% by mass of salt, and 10% by mass of water was heated at the temperature described in Table 5 and aged for 3 days. Aged egg yolk of Examples 3 to 5 was obtained.
Subsequently, Examples 3 to 5 and the above-mentioned salted egg yolk samples were treated with a TCA solution in the same manner as in Test Example 1 to precipitate proteins, and the absorbance of the supernatant at a wavelength of 280 nm was measured. And the value of the light absorbency of the matured egg yolk of each Example with respect to salted egg yolk was calculated | required. The results are shown in Table 5.

[Results of absorbance (Examples 3 to 5)]
As shown in Table 5, the absorbance values of the samples of Examples 3 to 5 with respect to salted egg yolk are in the range of 2.7 (Example 3) to 3.5 (Example 5), and the above comparison Even compared with Example 1 (absorbance value 1.21), it was a sufficiently high value.
It was also confirmed that the absorbance value slightly decreased as the aging temperature increased from 57 ° C. (Example 5) to 61 ° C. (Example 3). From this result, it was confirmed that when the egg yolk was used, many egg yolk protein degradation products were produced at around 60 ° C., particularly around 57 ° C.
In addition, about Examples 3-5, the tendency for a viscosity to increase was also seen as the ripening temperature rose. This will be described later.

[Preparation of Examples 6 to 26 and Measurement of Absorbance]
Then, in order to examine more various conditions, the matured egg yolk of Examples 6-26 was prepared. First, egg yolk was obtained by the same method as in Example 2. Next, the obtained egg yolk, egg yolk, salt and water were mixed in the proportions shown in Tables 6 and 7. Subsequently, the mixture was heated at a predetermined temperature and aged for the time indicated in each table to obtain aged egg yolk of Examples 6 to 26.
On the other hand, Comparative Examples 2 and 3 were all prepared from the mixture in the ratios shown in each table, and were used for the test without heating and aging.
And the light absorbency of the sample with respect to salted egg yolk was calculated | required similarly to Examples 1-5 with respect to the samples of Examples 6-26. The results are shown in Tables 6 and 7.

[Results of Absorbance (Examples 6 to 11 and Comparative Example 2)]
As shown in Table 6, in Examples 6 to 11 and Comparative Example 2, the amount of egg yolk and the aging time were mainly different.
In Examples 6 and 7 and Comparative Example 2 in which the amount of egg yolk was 3% by mass, the aging time became longer as 0 hours (Comparative Example 2), 170 hours (Example 6), and 288 hours (Example 7). It was confirmed that the absorbance values increased to 1.2, 6.5, and 8.1. In Comparative Example 2 which was not particularly aged, the absorbance value was 1.2, which was a low value of less than 1.5.
Moreover, the same tendency was also seen in Examples 8 and 9 where the amount of egg yolk was 1% by mass and Examples 10 and 11 where 10% by mass.
From these results, it was confirmed that when the aging time was 300 hours or less, the absorbance value tended to increase as the aging time increased.
On the other hand, in Examples 6 and 8 in which the ripening time is 170 hours, Example 6 in which the amount of egg yolk is 3% by mass is higher in Example 6 than in Example 8 in which the amount of egg yolk is 1% by mass. It was confirmed that the value was increased (6.5 in Example 6, 2.9 in Example 8). Furthermore, in Example 10 where the amount of egg yolk was increased to 10% by mass and the aging time was 72 hours, the absorbance value was 3.8. This value is larger than Example 9 (absorbance is 3.4 above) in which the amount of egg yolk was ripened for 245 hours at 1% by mass, and Example 4 (absorbance value is 2) with the same aging time and aging temperature. .8).
Thereby, it was confirmed that by increasing the amount of egg yolk, a large amount of egg yolk protein degradation product was produced, and the ripening time could be shortened.
Moreover, in Example 11 where the amount of egg yolk is as large as 10% by mass and the aging time is as long as 200 hours, the absorbance value is as high as 10.8, and both the amount of egg yolk and the aging time are both high. It was confirmed to have a correlation with the absorbance value.

[Results of Absorbance (Examples 12 to 21 and Comparative Example 3)]
As shown in Table 7, in Examples 12 to 21, the aging time was different between 158 hours (Example 12) and 180 hours (Example 21).
In Examples 12 to 21 in which the aging time was in the above range, the absorbance value was 6.5 (Examples 18, 19 and 20) or more and 7.2 (Example 14) or less, both of which were high values. . On the other hand, in Examples 12 to 21, no relationship was found in which the absorbance value increased as the aging time increased. From this, it was confirmed that when the aging time is about 160 hours to 180 hours, a high absorbance can be stably obtained.
On the other hand, in Comparative Example 3 that was not aged, the absorbance value was 1.3, which was a low value of less than 1.5, as in Comparative Example 2.

[Results of absorbance (Examples 17, 22, and 23)]
As shown in Table 7, in Examples 17, 22 and 23, the egg yolk content and the water addition rate were different. The water content was set so as to increase as the egg yolk content decreased.
From these results, as the yolk content decreased to 91.8% by mass (Example 17), 83.0% by mass (Example 22), and 73.0% by mass (Example 23), the absorbance increased. It was confirmed that the values decreased to 6.5 (Example 17), 6.2 (Example 22), and 5.5 (Example 23). Thus, it was confirmed that the absorbance value increases as the amount of egg yolk as the base of the egg yolk protein degradation product increases.

[Results of absorbance (Examples 24-26)]
As shown in Table 7, in Examples 24 to 26, the aging temperature was different within the range of 55 ° C to 65 ° C.
In Example 24 where the aging temperature was 55 ° C., the absorbance value was 6.9, and in Example 25 where the aging temperature was 57.5 ° C., 7.0, which was almost the same value. On the other hand, in Example 26 where the aging temperature was 65 ° C., the absorbance value was 3.6, which was significantly lower than those in Examples 24 and 25. From this, it was confirmed that when the egg candy was used, ripening proceeded particularly at a ripening temperature of about 55 ° C. to 60 ° C., and many egg yolk protein degradation products were produced.

<Test Example 3: Measurement of viscosity and pH>
In order to further analyze the physical properties of the matured egg yolk of the present invention, the viscosity and the pH were measured using the above Examples 3 to 5, 22 and Examples 27 and 28.

[Production of Examples 27 and 28]
In order to confirm the change in physical properties due to freezing and thawing and heating, Examples 27 and 28 were produced by further processing the mature egg yolk of Example 22.
In Example 27, the matured egg yolk of Example 22 was stored frozen at -30 ° C for one month and thawed.
In Example 28, the matured egg yolk of Example 22 was heated at 75 ° C. for 30 minutes.

[Measurement and result of pH]
With respect to the matured egg yolk (Examples 3 to 5) and the above Examples 22, 27, and 28 that were aged at each temperature of 57 ° C to 61 ° C, a pH meter (desktop pH meter manufactured by Horiba, Ltd.) at 20 ° C. The pH was measured by F-72). Table 8 shows the measurement results.
In the matured egg yolks of Examples 3 to 5, 22, 27, and 28, the pH was 5.8, respectively. Thereby, pH of Examples 3-5, 22, 27, and 28 was 5.0 or more and 6.5 or less, and it was confirmed that it is close to the original pH of egg yolk.
Furthermore, when the pH of Examples 1 and 2 and Comparative Example 1 was measured in the same manner, pH of Example 1 was 5.1, pH of Example 2 was 5.5, and Comparative Example 1 was pH 6.7. Was 4.5 or more and 7.0 or less. When I ate these samples, I could feel the mellowness peculiar to egg yolk. In addition, when pH of Examples 6-26 was measured similarly, all were the range of 4.5 or more and 7.0 or less.

[Measurement and results of viscosity]
For the matured egg yolk (Examples 3 to 5, 22) aged at 57 ° C. to 61 ° C. and the aged egg yolks of the above Examples 27 and 28, the viscosity at a product temperature of 20 ° C. Machine Industry Co., Ltd., model number: BII type, rotor used: No. 5, rotation speed: 20 rpm).
Table 8 shows the measurement results.
As shown in the table, in Examples 3 to 5, the higher the aging temperature, the higher the viscosity. That is, the viscosity of Example 5 at 57 ° C., the lowest aging temperature, is 1.8 Pa · s, 7.4 Pa · s in Example 4 at 60 ° C., and 10.8 Pa · s in Example 3 at 61 ° C. Results were obtained. In Examples 3 to 5, unlike the dry liquid, it was confirmed that the viscosity (a feeling of thickening) like raw egg yolk or semi-live egg yolk was maintained.
The viscosity of Example 22 at an aging temperature of 60 ° C. was 9.8 Pa · s, which was close to that of Example 4.
On the other hand, Example 27 obtained by adding freezing and thawing treatment to Example 22 was 16 Pa · s, which was significantly higher than Example 22. Furthermore, in Example 28 in which Example 22 was heated to inactivate the enzyme, it was a higher 74 Pa · s. Thereby, after aging, it was confirmed that the viscosity of the matured egg yolk added with freezing and thawing treatment or heat treatment is increased.
Further, when the viscosities of Examples 1, 2, 6 to 21, 23 to 26 and Comparative Example 1 were similarly measured, it was confirmed that all were 1 Pa · S or more and 500 Pa · S or less.

<Test Example 4: Evaluation of lipid oxide>
Furthermore, in order to evaluate the lipid oxide in aged egg yolk, the relative fluorescence intensity was measured with respect to the samples used in Test Examples 1 to 3.

[Measurement of fluorescence intensity (salted egg yolk, Examples 1 and 2 and Comparative Example 1)]
First, a sample solution was prepared from the salted egg yolk, the samples of Examples 1 and 2 and Comparative Example 1, and the fluorescence intensity was measured.
Weigh 1 g of egg yolk in a 15 mL falcon tube and add 3 mL of ion-exchanged water with Pipetman. After stirring with a vortex mixer to obtain a suspension, 400 μL is taken from the suspension into a 15 mL conical tube. 3 mL of a mixed solution of diethyl ether: ethanol (1: 3) was added to the tube, and the mixture was well stirred with a vortex mixer.
After centrifuging at 1,200 g for 5 minutes, the mixture was filtered through a 0.45 μm pore size filter, and the resulting supernatant was used as a sample solution.

  The obtained sample solution was put in a quartz cell, and fluorescence intensity at Ex 360 nm and Em 440 nm was measured with a fluorescence spectrophotometer (model name “U-3210”, manufactured by Hitachi, Ltd.). However, each fluorescence intensity showed the fluorescence intensity on the same conditions of standard solution (A standard solution was obtained by melt | dissolving 1 microgram quinine sulfate in 1 mL of 0.05 mol / L sulfuric acid aqueous solution) with relative fluorescence intensity.

  Table 9 shows the measurement results. In Table 9, the value obtained by multiplying the relative fluorescence intensity by 100 is shown.

[Results of fluorescence intensity (salted egg yolk, Examples 1 and 2 and Comparative Example 1)]
As shown in Table 9, the salted egg yolk used as a control had a low relative fluorescence intensity of 1.10. On the other hand, in Examples 1 and 2, the relative fluorescence intensities were 2.31 and 2.18, respectively, and both were 2.0 × 10 ⁻² or more (1.5 × 10 ⁻² or more). Further, Comparative Example 1 also had a relative fluorescence intensity of 2.16, similar to Examples 1 and 2.
From this, it was confirmed that the lipid oxide increased by maintaining at a predetermined temperature (for example, 55 ° C.) for 3 days.

[Measurement of fluorescence intensity (Examples 7 to 10, 14, 20, 22 to 26 and Comparative Examples 2 and 3)]
In response to the results of Example 1 and the like, the relative fluorescence intensity was measured in the same manner for the matured egg yolk produced under various conditions, and the lipid oxide was evaluated. The results are shown in Table 10.

[Results of fluorescence intensity (Examples 7 to 10, 14, 20, 22 to 26 and Comparative Examples 2 and 3)]
As shown in Table 10, in Examples 7 to 10 and 14, it was confirmed that the value of the relative fluorescence intensity tends to increase as the aging time becomes longer.
Specifically, in Example 10 where the aging time is 72 hours and Example 8 where the aging time is 170 hours, the relative fluorescence intensities are 2.27 × 10 ⁻² and 3.74 × 10 ⁻² , respectively. 0.0 × 10 ⁻² or less. In contrast, in Example 9 where the aging time was 245 hours and Example 7 where the aging time was 288 hours, the relative fluorescence intensities were 6.60 × 10 ⁻² and 8.87 × 10 ⁻² , respectively. It was a value larger than 0 × 10 ⁻² .
The relative fluorescence intensities of Comparative Examples 2 and 3 with an aging time of 0 hour were 0.90 × 10 ⁻² and 1.00 × 10 ⁻² , respectively, which were low values of less than 1.5 × 10 ^−2. It was.
Thereby, by setting the aging time to 24 hours or more and 240 hours or less, for example, 192 hours or less, the relative fluorescence intensity is 1.5 × 10 ⁻² or more and 5.0 × 10 ⁻² or less, and further 2.0 × 10 it was confirmed to be suppressed to ^-2 4.0 × ^{10 -2} or less.

In addition, when the samples of Examples 7 to 10 and 14 were eaten, in Examples 8, 10 and 14 in which the relative fluorescence intensity was 2.0 × 10 ⁻² or less and 4.0 × 10 ⁻² or less, astringency (astringency taste) There was almost no umami and rich taste, and the taste was very good. On the other hand, in Examples 7 and 9 in which the relative fluorescence intensity was larger than 5.0 × 10 ⁻² , although the taste was good, a slight astringency was felt. Thereby, the astringent taste can be suppressed by setting the relative fluorescence intensity of the eggplant to 1.5 × 10 ⁻² or less and 5.0 × 10 ⁻² or less, and further 2.0 × 10 ⁻² or less to 4.0. It was confirmed that a better taste was obtained by setting it to 10 × ⁻² or less.

In addition, from the results of Examples 20, 22 and 23 in which the aging time was around 170 hours, it was confirmed that the value of the relative fluorescence intensity had a correlation with the content of egg yolk.
Specifically, the relative fluorescence intensity of Example 23 having an egg yolk content of 73.0% by mass was 3.16 × 10 ⁻² . On the other hand, in Example 22 where the content of egg yolk is 83.0% by mass, it is 3.40 × 10 ⁻² , and in Example 22 where the content of egg yolk is 91.8% by mass, it is 3.77 × 10 ⁻² . In addition, as the egg yolk content increased, the value of the relative fluorescence intensity gradually increased. Thereby, it becomes easy to adjust the value of relative fluorescence intensity to 4.0 * 10 ^<-2> or less by suppressing the production | generation of egg yolk lipid oxide by making content of egg yolk containing egg yolk lipid 90% or less. Was confirmed.

Furthermore, the fluorescence intensities of Examples 24 and 25 having aging temperatures of 55 ° C. and 57.5 ° C. are 4.17 × 10 ⁻² and 4.49 × 10 ⁻² , respectively, and 1.5 × 10 ⁻² or more. It was 5.0 × 10 ⁻² or less. On the other hand, the fluorescence intensity of Example 26 having an aging temperature of 65 ° C. was 8.60 × 10 ⁻² , which was larger than 5.0 × 10 ⁻² . When these aged egg yolks were eaten, all of them had a good taste, but in Example 26, the astringent taste was felt stronger than in Examples 24 and 25.
Therefore, it was confirmed that by setting the aging temperature to 45 ° C. (50 ° C.) or more and 60 ° C. or less, the formation of lipid oxide can be suppressed and the astringent taste can be suppressed.

<Test Example 5: Aged egg yolk aged using rice bran>
Subsequently, an aged egg yolk was produced using rice bran instead of egg yolk, and the absorbance and other physical properties were confirmed.

[Example 29]
The matured egg yolk of Example 29 was produced in the same manner as in Example 19 except that the egg cake of Example 19 was changed to rice bran (manufactured by Marcome Co., Ltd.).
The salt content of the resulting mature egg yolk was 4% by mass.
In addition, what was preserve | saved the obtained mature egg yolk in a 4 degreeC low temperature room | chamber was used for each analysis mentioned later.

For the matured egg yolk of Example 29 and the salted egg yolk having the same salt content (4% by mass), the absorbance at 280 nm of each supernatant was measured by the method described above. As a result, the absorbance of the mature egg yolk was 0.504, the salted egg yolk was 0.110, and the absorbance of the mature egg yolk with respect to the salted egg yolk was 4.6.
The relative fluorescence intensity was 7.7 × 10 ⁻² .
The pH at the product temperature of 20 ° C. was 5.8, and the viscosity was 35 Pa · S (rotor: No. 6, 20 rpm, when the product temperature was 20 ° C.).

  When the aged egg yolk of Example 29 was eaten, the mellow flavor peculiar to egg yolk was felt, and the taste was good. From this, it was confirmed that the matured egg yolk of the present invention is not limited to egg yolk but can also be used that is made from other raw materials.

<Test Example 6: Aged egg yolk aged with cheese>
Subsequently, an aged egg yolk was produced using cheese with blue mold and white mold in place of strawberries, and the absorbance and other physical properties were confirmed.
[Example 30]
First, using commercially available blue cheese, 4 parts by mass of salt and 3 parts by mass of blue cheese were mixed with 93 parts by mass of liquid egg yolk, and aged for 156 hours in a 60 ° C. incubator. Got. The salt content of the mature egg yolk of Example 30 was 4.1% by mass. In addition, what was preserve | saved the obtained mature egg yolk in a 4 degreeC low temperature room | chamber was used for each analysis mentioned later.

The absorbance at 280 nm of each supernatant was measured by the method described above for the mature egg yolk of Example 30 and the salted egg yolk having the same salt content (4.1% by mass). As a result, the absorbance of the mature egg yolk was 0.188, the salted egg yolk was 0.110, and the absorbance of the mature egg yolk with respect to the salted egg yolk was 1.7.
The relative fluorescence intensity was 1.8 × 10 ⁻² .
The pH at the product temperature of 20 ° C. was 6.1, and the viscosity was 368 Pa · S (rotor No. 7, 10 rpm, when the product temperature was 20 ° C.).

  Furthermore, when the matured egg yolk of Example 30 was eaten, umami, richness, and slight bitterness were added to the mild flavor unique to egg yolk, resulting in a deep taste.

[Example 31]
The aged egg yolk of Example 31 was produced in the same manner as Example 30 except that the commercially available Camembert cheese was used instead of the commercially available blue cheese. The salt content of the obtained mature egg yolk was 4.1% by mass.

The absorbance at 280 nm of each supernatant was measured by the method described above for the mature egg yolk of Example 30 and the salted egg yolk having the same salt content (4.1% by mass). As a result, the absorbance of the mature egg yolk was 0.190, the salted egg yolk was 0.110, and the absorbance of the mature egg yolk with respect to the salted egg yolk was 1.7.
The relative fluorescence intensity was 2.1 × 10 ⁻² .
The pH at 20 ° C. was 6.1 and the viscosity was 384 Pa · S (rotor No. 7, 10 rpm, at 20 ° C.).

  Furthermore, when the matured egg yolk of Example 31 was eaten, umami, richness, and slight bitterness were added to the mellow flavor peculiar to egg yolk, resulting in a deep taste.

<Test Example 7: Processed Food Using Aged Egg Yolk>
Finally, various processed foods were made using aged egg yolk.
[Example 32]
Mayonnaise was produced by a conventional method using the aged egg yolk obtained in Example 1 according to the following blending ratio.

(Mayonnaise mix ratio)
Edible oils and fats 70%
Vinegar 9%
Yolk 5%
Aged egg yolk (salt content 4%) 1%
Sodium glutamate 2%
Salt 2%
Shimizu 11%
――――――――――――――――――
Total 100%

  When the obtained mayonnaise was eaten, a taste of a mature egg yolk suitable for mayonnaise was felt.

[Example 33]
Carbonara sauce was produced by a conventional method using the aged egg yolk obtained in Example 1 according to the following blending ratio.

(Mixing ratio of carbonara sauce)
Edible oils and fats 40%
Reduced starch saccharified product (Niseki Kasei Co., Ltd., "S30") 32%
Whole milk powder 15%
Cheese powder 5%
Salt 4%
Yolk 2%
Aged egg yolk (salt content 4%) 1%
Sodium glutamate 0.8%
Xanthan gum 0.1%
Black pepper 0.1%
―――――――――――――――――――――――――――――――
Total 100%

  When the obtained carbonara sauce was eaten, the taste of a mature egg yolk suitable for carbonara sauce was felt.

[Example 34]
According to the following blending ratio, the egg spread obtained in Example 2 was used to produce an egg spread by a conventional method.

(Combination ratio of egg spread)
Boiled egg 76%
Mayonnaise 17%
Modified starch 1%
Nisin 0.5%
Salt 0.2%
Aged egg yolk (salt content 4%) 1%
Sodium glutamate 0.8%
Xanthan gum 0.1%
Shimizu 3.4%
――――――――――――――――――――――
Total 100%

  When the obtained egg spread was eaten, the taste of a mature egg yolk having a good taste suitable for the egg spread was felt.

[Example 35]
According to the following blending ratio, a potato salad was produced by a conventional method using the aged egg yolk obtained in Example 2.

(Mixing ratio of potato salad)
Mayonnaise 14%
Potato 48%
Cucumber 6%
Carrot 6%
Onion 6%
Corn 6%
Cabbage 6%
Lettuce 6%
Aged egg yolk (salt content 4%) 1.5%
Super white sugar 0.3%
Salt 0.2%
――――――――――――――――――――――――
Total 100%

  When the obtained potato salad was eaten, a taste of a good ripened egg yolk suitable for the potato salad was felt.

[Summary]
From the above results, when the egg yolk added with salmon and salt is aged while being heated at a low temperature of 40 ° C. to 65 ° C., the absorbance to the salted egg yolk in the supernatant after the treatment with the TCA solution is 1.5 times or more. It was confirmed that a mature egg yolk of 0 times or less could be produced.
By setting the absorbance within the above range, the umami and richness derived from egg yolk protein degradation products can be sufficiently obtained, and these can be mixed with the original flavor of egg yolk to obtain a matured egg yolk having a good taste. Further, by setting the content of glutamic acid, aspartic acid, valine, leucine and lysine as free amino acids to 2 g or more and 7 g or less per 100 g of protein, the umami and richness peculiar to amino acids are mixed and a more preferable mature egg yolk can be obtained. it can.
Furthermore, it was confirmed that the salt content of the matured egg yolk can be adjusted to 12% by mass or less by adjusting the amount of salt added and the like, and a matured egg yolk containing no excessive salt that impairs the taste and richness can be produced. .
In addition, the aging time is 10 days (240 hours) or less, further 8 days (192 hours) or less, and the aging temperature is 45 ° C. (50 ° C.) or more and 60 ° C. or less, so that the relative fluorescence intensity of the lipid oxide is increased. It can adjust to the range of 1.5 * 10 ^<-2 > or more and 5.0 * 10 ^{< -2} > or less. Therefore, it was confirmed that the mature egg yolk of the present invention can moderately suppress the formation of lipid oxides and obtain a good taste with less astringency.
In addition, from the results of Examples 30 and 31, even if an aged egg yolk is produced using cheese cultivated in place of strawberries, a unique richness and umami are added to the mellow flavor of the egg yolk. An aged egg yolk having a flavor was obtained. Thereby, it was confirmed that even if molds other than Neisseria gonorrhoeae were used, a mature egg yolk having umami and richness and good taste was obtained.
And from the result of Examples 32-35, it was confirmed that the matured egg yolk of this invention can be used for various processed foods, and can deepen the taste of the said processed foods.

Claims (12)

An aged egg yolk ripened from a mixture comprising edible mold that produces a proteolytic enzyme, egg yolk and salt,
The salt content is 1% by mass or more and 12% by mass or less,
An aged egg yolk having an absorbance of 1.5 times or more and 15.0 times or less with respect to the salted egg yolk measured by the following method.
<Measurement method of absorbance of aged egg yolk and salted egg yolk>
(1) Each of the mature egg yolk and the salted egg yolk having the same salt concentration (mass%) as the mature egg yolk is accurately weighed in an amount of 0.5 g, and each of the mature egg yolk and the salted egg yolk thus weighed is 20 mL of ion-exchanged water. Add and stir uniformly to suspend.
(2) 10 mL of a 10% by mass trichloroacetic acid solution is added to each of the matured egg yolk and the salted egg yolk, stirred again and uniformly suspended, and then allowed to stand for 30 minutes.
(3) The aged egg yolk and the salted egg yolk after standing are centrifuged at 3500 rpm for 10 minutes, and the aged egg yolk and the salted egg yolk after centrifugation are further filtered through a 0.45 μm filter to obtain a supernatant. .
(4) Using a spectrophotometer, the absorbance of each of the mature egg yolk and the salted egg yolk supernatant at 280 nm is measured, and the measured values are set as the absorbance of the mature egg yolk and the absorbance of the salted egg yolk, respectively. The absorbance of the mature egg yolk relative to the salted egg yolk is calculated by dividing the absorbance by the absorbance of the salted egg yolk. Aged egg yolk according to claim 1,
Aged egg yolk including salmon. Aged egg yolk according to claim 2,
An aged egg yolk in which the cocoon is an egg candy obtained by culturing koji mold with eggs. Aged egg yolk according to any one of claims 1 to 3,
Aged egg yolk having a content of glutamic acid, aspartic acid, valine, leucine, lysine and salts thereof as free amino acids contained in the aged egg yolk is 2 to 7 g per 100 g of protein. The mature egg yolk according to any one of claims 1 to 4,
Aged egg yolk having a pH of 4.5 or more and 7.0 or less. Aged egg yolk according to any one of claims 1 to 5,
Aged egg yolk having a viscosity measured at a product temperature of 20 ° C. of 1 Pa · S or more and 500 Pa · S or less. Aged egg yolk according to any one of claims 1 to 6,
An aged egg yolk containing at least one aroma component selected from tiglinaldehyde, 2-pentylfuran, methylpyrazine, trans-2- (2-pentenyl) furan, 2,4-heptadienal, methional, and phenylacetaldehyde. The aged egg yolk according to any one of claims 1 to 7,
Aged egg yolk having a protein content of 16% by mass or less. Processed food using the matured egg yolk according to any one of claims 1 to 8. Producing a mixture of edible mold producing proteolytic enzyme , egg yolk and salt;
Producing a matured egg yolk having a salt content of 1% by mass to 12% by mass by aging the mixture while heating at 40 ° C to 65 ° C. A step of producing a mixture obtained by mixing a koji mold cultured with koji mold, egg yolk, and salt;
Producing a matured egg yolk having a salt content of 1% by mass to 12% by mass by aging the mixture while heating at 40 ° C to 65 ° C. A method for producing an aged egg yolk according to claim 11,
The method for producing an aged egg yolk, wherein the koji is an egg koji obtained by culturing koji mold with eggs.